I have several websites I visit daily that crack me up! Most of them are from the the Cheezburger Network, who brings you LOLCats. Be sure to check out all of their sites, I am partial to Pundit Kitchen and Fail Blog myself! Also awesome are:
Savage Chickens post-it note chickens who hate their jobs, have mutant powers or are zombies.
Picture is Unrelated bizarre photos of crazy shit.
XKCD nerdy webcomic.
This is Photo Bomb the art of ruining other peoples' photos.
It Made My Day twitter-sized bits of poetic justice or other happiness.